Elliptic spring



(No Model.)

W. DAVISON.

ELLIPTIO SPRING. No. 314,919. Patented Mar.3l, 1885.

INVENTUW W MQK W U ITED STATES PATENT OFFICE.

"WILLIAM DAVISON, OF HOBOKEN, NEV JERSEY.

ELLIPTIC SPRlNG.

.LBI ECIFICATIGH forming part of Letters Paten No. 314,919, dated March 31, 1885.

Application filed January 30, 1884. Renewed January 27, 1585. (No model) To all whom, it may concern.-

Be it known that 1, WILLIAM DAVISON. a

subject of the Queen of Great Britain, residing 3 at Hoboken. in the county of Hudson and State of New Jersey, have invented new and useful Improvements in Elliptic Springs, of which the following is a specification.

My invention relates to elliptic and semielliptic springs made of plates of concavoconvex form in cross-section, and arranged in the spring with the concave sides of the plates on the outer or crowning sides of the longitudinal'bend, and with the convex sides on the longitudinally-concave side of the spring, so that the edges of the plates of the spring are subject to compression in service, and the tension is sustained by the web of metal between the edges by which the metal is disposed in the spring so as to sustain the greatestweight of load for a given quantity of metal in the spring.

My invention consists of the short outside or top plate of the spring, constructed, as hereinafter described, for graduating the spring better and making it more substantial and durable than as heretofore constructed, reference being made to the accompanying drawings, in which- Figure l is a perspective View of my improved top plate. Fig. 2 is a plan View of said plate. Fig. 3 is a perspective View of the complete spring. Fig. 4 is a section of the top plate on the line as w of Fig. 2. Fig. 5 is a section on the line 3 y of Fig. 2. Fig. 6 is a transverse section on line 2 z, and Fig. 7 is a transverse section of the plates of the spring through the middle.

I make a top plate of transversely-convex form its whole length on the longitudinal concave or inner side that is to fit in the concave outer side of the second plate of the spring, with the middle portion, a, of said top plate fiat on the upper or out side, and the end portions, 1), concave transversely and tapering in thickness from the ends of the fiat portion to the ends of the plate. I also taper the edges of the said top plate to a point at the ends, beginning back of the ends a distance equal to the width of the plate, and constructing said taper edges on a curve the radius of which is the width of the plate, and I also 5 construct the points h of all the other plates, t, of the spring, exceptthe main platej, in the same form, which, together with the transverse 1 concuvo convex curvatures ofthe plates formed on the same radius, as represented in Fig. 7, and with the arrangementof the plates in uniformity as to the distances between the ends of the superimposed 1:)lates,'insures almost perfect uniformity in the movements of the spring for given weights in closing under the load. I make the flat section a of the top plate a little longer than the width of the band d by which the plates are bound together, so that the ends a of the flat section will be extended beyond the ends of the band to sepa rate these points for better graduation, and I also extend the ends of the said top plate beyond the ends of the fiat section a, so that the curves f of the taper ends vanish in the edges of the plate at the points 9 some distance from the ends 0, while the taper of the thickness of the plate both along the edges and in the concaves 6 extends from the points it to the ends 6 of said taper sections for graduation of said section a of the top plate is about as much thicker than the depth of the concavity to be filled by it in the second plate as the thickness of the other plates of the spring, so that from the edges of the band to about where the taper edges of the points begin at g the edges of the top plate rise about the same above the second plate as the edges of the other plates are above the plates below them, and from these points the ends of the top plate taper both in thickness and breadth in the same measure as the ends of the other plates. By this construction of the top plate the springs are graduated at the top and directly from the band, so as to give the best results in practice as to uniformity.

Numerous tests of springs made with top plates, as herein described, and with thetaon the same radius as the points of said top plates have invariably given practically the same extent of closing of the spring for the same amount of additional weight throughout the whole range from the beginning to the limit of the load.

When I speak of the top plate I mean the concave and tapered ends. The plano-convex per points of the intermediate plates curved semi-elliptic springs made with coneavo-con-..

vex, intermediate, and main plates, having the plano-convex middle section, a, and con cave-convex ends, said ends being tapered at the edges f on a radius equal to the breadth of the plate, substantially as described.

3. The combination, in an elliptic or semielliptic spring, ofa top plate having the planoconvex middle section, a, and concavoeonvex pointed ends, with intermediate concavo-convex plates having similarly-pointed ends, and a main plate of concavo-convex form with fiat ends, substantially as described.

4. The combination, in an elliptic or semielliptic spring, of a top plate having the middle plano-convex section, a, and concavo-con vex tapered ends with edges f formed on a radius equal to the width of the plate, intermediate plates also having pointed ends formed on the same radius, and a main plate, said interniediate and main plates being concavoconvex in cross-section and the transverse curvature of all the plates being formed on a radiusequal to the Width of the plates, substantially as described.

In witness whereof I have hereunto signed my name in the presence of two subscribing witnesses.

WILLIAM DAVISON. Witnesses:

V. J. llIORGAN, S. H. MORGAN. 

